1. Field of the Invention
The present invention relates to a display, and more particularly to a display that is capable of multi-touch sensing, and a driving method thereof.
2. Description of the Related Art
Generally, a touch panel is a type of user interface that may be attached to a surface of a display device, where an electrical characteristic is changed at a touch area where a finger of a user or other instrument contacts the touch panel so as to sense the touch area thereof. The application for touch panels extends to small portable terminals, office equipment and the like. If two or more touches are simultaneously generated, the touch panel might malfunction or any one of the touches may be selected by a pre-set program.
FIGS. 1-3 show known multi-touch devices that have attempted to overcome the limitations of multi-touch recognition systems.
Referring to FIG. 1, the multi-touch device of the related art includes a transparent acrylic plate 11, first through fourth IRLED (infrared or IR light-emitting diode) arrays 12A-12D, and first through fourth IRPD (infrared or IR photo-detector) arrays 12A to 12D. The IRLED arrays and IRPD arrays 12A to 12D include a plurality of IR light emitting diodes 13 and a plurality of IR photo detectors 14.
FIG. 2 shows that a hand of the user or a pen is directly in contact with the transparent acrylic plate 11.
The IRLED and IRPD arrays 12A to 12D are arranged to face a side surface of the transparent acrylic plate 11.
Infrared light is radiated from the IRLED 13 through the transparent acrylic plate 11. The infrared light is received by the corresponding IRPD 14. In this state, if a hand or a pen is in contact with the transparent acrylic plate 11, the infrared light is scattered and is not received at the corresponding IRPD 14 on the contact (or touch) area. Accordingly, the multi-touch device in FIG. 1 may recognize an erroneous touch location.
A multi-touch device of the related art in FIG. 1 has an advantage of being thin. However, the multi-touch device of the related art is disadvantageous because the multi-touch recognition is inaccurate due to direct illumination by infrared light. Further, the effective display surface is reduced by the area occupied by the IRLED and IRPD arrays 12A to 12D.
FIG. 2 and FIG. 3 show a projector-type multi-touch device.
The multi-touch device includes a camera and projector module 30, which are located at a rear portion of the transparent acrylic plate 11.
If a finger of the user is in contact with an arbitrary point on the transparent acrylic plate 11, an infrared ray is scattered by the finger or other object. The scattered infrared ray is incident on the camera and projector 30. Such a scattered infrared ray SIR is sensed so that the projector-type multi-touch device can sense a multi-touch area.
However, because the distance between the transparent acrylic plate 11 and the camera and projector module 30 is relatively long, the multi-touch device in FIG. 2 and FIG. 3 occupies a wide space. Furthermore, since the multi-touch device in FIG. 2 and FIG. 3 displays an image using a projector, the type of display device and the design of the display device is limited. Additionally, the life span of the projection lens is limited.
The multi-touch devices in FIG. 1 to FIG. 3 transmit signals from the camera and projector module 30 to an external computer via a cable, and process the signals by an external computer. Thus, the system is complicated, the space occupied by the components is large, and a signal transmitting path is relatively long.